Automatic navigator



Sept. 26, 1961 v. CARBONARA AUTOMATIC NAVIGA'I'OR 8 Sneets-Sheet 2 Filed D90. 19, 1950 Sept. 26, 1961 v. E. CARBONARA AUTOMATIC NAVIGATOR 8 Sneets-Sheet 5 Filed Dec. 19, 1950 IIIIIIIIIIIIIIIIIIIIIIIIIII.IIIII----------IIIIIIIIIIIII IIIIIIISIIIIIIIIIIIIIIIIIIIIIIIIIIIII-IIIIIIIIIIIIIIIIII P 1961 v. E. CARBONARA 3,001,289

AUTOMATIC NAVIGATOR Filed D60. 19, 1950 8 Sneets-Sheet 4 Sept. 26, 1961 v. E. CARBNARA AUTOMATIC NAVIGATOR 8 Sneets-Sheet 5 Filed Dec. 19, 1950 Sept. 26, 1961 v. CARBONARA AUTOMATIC NAVIGATOR 8 Sneets-Sheet 6 Filed. D60. 19, 1950 IN VEN TOR.

V/C7'0P 5 cneeozvnen BY Sept. 26, 1961 v. E. CARBONARA AUTOMATIC NAVIGATOR 8 Sneets-Sheet 7 Filed Dec. 19, 1950 INVENTOR V/(7'02 s. aqzeaxmen /777'FWEK Sept. 26, 1961 v. E. CARBONARA AUTOMATIC NAVIGATOR 8 Sneets-Sheet 8 Filed D60. 19, 1950 3A10LZ89E al Patented Sept. 26, 19 61 This invention relates to n iitomatic riavigtion-ri strument for use in movingvehiclessuch as air 01" sea craft and more particularly to an automatic star follwing device through which a"cdntimous indication of longitude and latitude of the movingwehicle-rnay be derived.

tlae telescope"platform"parallel totlie support and with The object of the present"invention is to provide a means for automatically con1biing t lie coordnates] of azimuth and elevation of a plurality of celestial bodies with the proper indication ofhour angl e in order to derive a continuous movemerit respbnsive-to or an indication of both longitude and latit1 de.

An object of the invention is the provision of an auto rnatic navigation instrument which the positionof a plurality of rigidly connected telescopes in spaoe by their relation to a plurality of celestial ponts of re ference and combines the position with a local horizontal and a local hour angle to provide a response governed by both the longitude and latitude of the instrument.

Another object of the invention is theprovison of an automatic navigation instrument including a platform, in fact or in eiect fixed in space by the direction of a pluralty of telescopes mountedon said platform toward a plurality of celestial points of reference constituted by sources of radiant energy, togeiher with a local horizontal correlated with the angle of said pltform about theeastwest axis to give a latitude response and with a means operated by local honr angle and correlated with the angle of said platform about the north-onth axis to give alongitude response.

A further object of the present irvention in ccordanc with the preceding object is the provisionof a rreans for deriving a cntinuous indication of longitude and ltitude by developing latitude from the cornparis on of the elvation of a substantially fixed celestial body with the local vertcal and by developirg longitude from the comparison of local hour angle and the azimuth hearing of a second celestial body having an apparent rotation about the first celestial bdy. A further object of the present ifivention is the provision of a mean for deriving a local Vertical to which the elevaton of a ceiestial body may be compared in order to derive a true ndication oflatitude. A further object of the invention is an atmatie navigation instrument including a plurality of telescopes positionable in elevationand azimuth so asto fellow a plurali=ty of celestial pointe of reference so that said telescopes and directly associated elements becornefixed in space regardless of the movement ofthe craft on which the in strument is mounted together with means providng a local horizontal to which the elevation of said telescopes is compared to provide a response governed by the latitude of the instrument and meansoperated by local hour parts shovv'n in seotion FIGURE 3 ;iselevational view from the left" of FIG- 2 with partsshowvn in secton. FIGUR 4 is a viticl setioi1al view along the line IV-IV o FIGURE 3:

FIGURES s"an enlgd sectional view of "FIGURE 4 eii'clsed in areaV.

FIGURE 6 isasec'tional view of the telescope shutter m'chnisns takn alngtlle VI- VI of FIGURE 4. FIGURE 7 is verical sectional view of the telescope shutter operating meeh'anisnr taken along the lines VIIVII FIGURE 6.

FIGURE8 is a vertical sectional view of the horizonta l r'ef ererc takeii long the lineVIII-VIII of FIGURE 4. FIGURE 9is a" schematie representation of the light sehlsitiescanning system controlling the operating motors the portin FIGU E""10 is a "viewof a shutter disc used in the navigator "and scanning systen.

FIGURE 11 is a scheinatic representation of the longitdecounterand resdlving unit of the present invention.

FIGURE 12 is a sehematic representation of the latitude counter and }'6S01Vlg unit of the present invention Principlesbj aperation The prjection of die -g eographical plane estblishing the eqi1atbr ont the celestial sphe re establishes the" equi-;

noctial andthe su-i1s path witl ain the celes tial sphere asit crosses the ecui1iootialestablishes the vernal and autumnal equinx, the vernal equinox being the spring time crossing of the sun over the equinoctial for this hemisphreand the autumnal being the fall crossing. The vernalequinox and theeqninoctial are then used as ba'ses front which to measure sdereal hour angle and declina tion which correspond tocelestial longitude and latitude respectively. The rotation of the earth causes the sidereal angle andocumbining with the azimuth of the telescopes to provide a response governed instrument.

Further objects and features of the inventionwill be readily apparent to those skilled in the art from the specification and appended drawingsillustratngcertain preferred embodiments in which:

FIGURE 1 is a perspective view of the au=torriatic navi gator of the present invention with the telescopelplatform tilted with respect to the support.

FIGURE 2 is an elevational view of the navigator with by the longit'ude of the hur7angle reference coordinates to rotaterelative tothe geographical longitude at a constant rate a completej cycle being a sdereal day. The iangular relatin be-"" tween the two coordinateysterrisg; i;e. the geographical and celestial, is oontinuously indicalted by a clck giving" Greenvvich sidereal time whioh, when measured in degrees of are, isknown as the Greenwieh houi"angle oftlie vernal equinox.

Any instantaneous position of the" earth within the celestial sphere may besi-rnulated by a mechnism rotatable about suitably ielated axes. Apointer mounted on a plane normal to itself is directed toward the nortkrcelestal pole, thus aligning tself in parallel with the p0lari" axis, theplane onwhich it is mounted being parallel tothe equatr. A secnd pointer"niounted at a uitble angle" I'QIJ'L the polar axis is directed toward ajsecondpoint 11" thecelestial sphere. Aslong as the two pointers are continually direoted toward these fixed pnts inspacetlie plane will rert1ain parallel with the equator and will not rotateWth the rotation of the earth, It will thus remain rigidly oriented in spa c e.

In practice, the pointers are aligned on two stars one of which, in the Northern Hemisphere, may conveniently 3 be Polaris which lies almost on the celestial pole conveniently aligns the polar pointer. (A deviating prism is, in practice, ernployed to direct light from Polaris parallel to the polar axis.) Any other suitably located bright star in the Northern Hemisphere may be used as the target for the second pointer to give the system the necessary spatial stability. Obviously, if tracking telescopes, as described in a copending application of Howard J. Eckweiler for Scanning System, Serial No. 95,768, filed May 27, 1949, which issued July 12, 1955 as Patent No. 2713,134 are substituted for the pointers, fixed spatial orientation will be automatically maintained.

It will be understood that any two or more celestial points of reference may be utilized with a corresponding number of telescopes so that a greater reliability and field of use will be provided for the event certain of the stars are obscured by the instruments position.

The above discussion contemplates a geographically fixed and rigid base for the telescope assembly, In practice, however, the assembly will be on a moving air or sea craft, and must, therefore, be capable of rotation in relation to the craft in which it is mounted. Assume, first that a grounded airplane is free to rotate, which rotation may be resolved about three mutually normal axes. Movements of the craft in altitude and azimuth can be compensated by the Polaris telescopes tracking mechanism about these axes. The whole assembly is supported on an azimuth shaft around which the Polaris telescope is free to maintan its northern orientation regardless of the motion of the arcraft about that axis. An axis normal to the azimuthal axis, and supported thereon, is consequently maintained approximately in an cast-west direction and serves for tracking Polaris in altitude.

The third axis of rotation of the airplane is about the axis normal to the azmuthal and cast-west axes. Motion around the polar axis by the second telescope does not compensate for this rotation, since, except at the geographical equator, the two axes do not coincide. However, when observed from a geographically fixed base, travel of the star along its diurnal circle about the polar axis is at a constant rate, and therefore, the second star could be followed around the polar axis by a clock-work mechanism. The tracking mechansm of the second telescope may then be used for stabilizing the star-following assembly about the third axis of the base.

The celestial eoordinates having been established, the location of geographical position requiresonly the deterrnination of the local vertical which is provided by a gravity-seeking device. The angular relation of the equator to the zenith, or local vertical, is latitude. Simlarly, longitude may be deduced from the angle between the meridian of the zenith and that of the second star.

With the automatic navigator mounted on a geograph ically fixed base, the direction of the vertical, of course, will not change. When, however, the base moves in a north-south direction, the vertical wll show a diierent orientation with respect to the polar telescopic axis. The instantaneous angular relation between the vertical and the equatorial plane indicates iatit'ude.

If the system is not moved in an cast-west direction, the angular relationship between the zenith and the vernal equinox in the celestial sphere is changing only as the earth rotates, and the clockwork mechanism mentioned above is adequate for the proper orientation of the system about the polar axis. However, if the base is moved in an cast-west direction, the direction of the zenith changes with relation to the vernal equinox at a rate which difiers from the advance of sidereal time, displacing the vertical. The angular relationship between the position of the vertical and the second star is one from which the local hour angle of the vernal equinox may be deduced. The difference between this angle and the Greenwich hour angle of the vernal equinox is longitude.

In the final mechanization of the automatic navigator of this invention, no clockwise is required to drive the and thus telescpic assembly around the polar axis. In stabilizing the system on the second star, the second telescope rotates the whole system including the vertical reference assembly about the third axis. In correcting for the resulting devation, the verticalreference actuates a motor which drives the telescopic assembly around its polar axis and forces the second telescope to recorrect about the third axis, thereby restoring the vertical reference. By this indirect action, the proper alignment of the telescopic assembly and the vertical reference assembly is maintained. The clockwork is then remotely placed and the local hour angle of the vernal equinox, as taken from the hour angle gear, is compared with the Greenwich hour angle on the clock. The diflerential between the two is transmitted to a counter where it appears as longitude.

Descriptian As shown in FIGURE 1, the automatic navigator of the present invention has mounted on the top of an hour angle gear plate 3 two seeking telescopes: telescope 1 which is oriented to seek Polaris, and telescope 2 which seeks a second star of strength comparable to Polaris such as Capella. Any desired nurnber of telescopes greater than one seeking any of the stars of sufficient magnitude for instrument response may be utilized in the navigator. The line of sight of each telescope is mechanically related to the supporting plate, the other telescope and the particular star it is to seek in the operation of the instrument. The hour angle gear 3 is mounted in a frame 4 which provides support for the associated light sensitive mechanism later to be described and has a pair of supporting hubs 5 rigidly secured to a pair of hollow rotatable shafts 44.

Shafts 44 are rotatably mounted in bearings 48 on trunnions 8 and 9 in the opposite sides of a cradle 11.

The cradle 11 is mounted for rotation about an axis at right angles to axis of rotation of the shafts 44 by means of a pair of arcuate races 15 at opposite sides of the cradle other than the sides on which the trunnions 8 and 9 are located, the races 15 cooperating with and being supported by a pair of stationary races 16 through a plurality of spaced hall bearings 17. The races 16 are mounted in a lower outer cradle 18. On the cradle 18 above the races 16 are mounted a pair of retainer wheels 21 upon stationary shafts 19. The outer cradle 18 is rotatably mounted through the bearings 26 and 27 upon a central stationary shaft 25 secured in the instrument mounting plate 29. A stationary gear ring 28 is rigidly Secured to the mounting plate and has gear test-h at its periphery meshing with teeth of -a pinion gear driven by a motor 24, the pinion and motor being supported upon the outer cradle 18 so that rotation of the motor is ac companied by rotation of the cradle 18 and the parts mounted thereon in azimuth about the central shaft 25. An azimuth scale and reference, one suitably mounted on the cradle 18 and the other fixed with respect to the mounting plate 29, provide for a setting or reading of. the azimuth of the instrument.

Mounted on the cradle 11 between and parallel to the races 15 is a geared sector 22. A motor 23 is mounted in the outer cradle 18 and drives a pinion which meshes with the teeth on the gear sector 22 to eiect rotation of the cradle 11 about an axis of rotation passing through the centers of development of the races 15, 16.

Rigidly mounted upon the shaft 44 at the right of the instrument, as viewed in FIGURES 1 and 2, is a geared sector 6. which meshes with a geared pinion driven by the motor 12 mounted upon the cradle 11. Rotation of the motor 12 is accompanied by rotation of the frame 4 and elements mounted therein about the axis of rotation of the shafts 44. Rigidly mounted upon the shaft 44 at the left of FIGURES 1 and 2 is a gear sector 7 which meshes with a pinion driven by a motor 13 mounted upon frame 14 which carries the horizontal reference to be hereinafter described, the pinion on motor 13 passing;

1 freely through an opening in the side of the cradle 11 adjacent thereto. Movement of theirame 14 will, as subsequently described, be determined by the differential rotaton between the sector 7 and the pinion driven by the motor 13.

-Shownin cross-section in FIGURE 4 is the mountingarrangement of the hour angle gear 3 upon which the -two telescopes, Polaris 1 and Capella 2, are mounted. A central supporting post 31 is secured to the [frame 4, as shown, and rotatably mounts the supporting sleeves 34 by bean'ngs 32 and 33, sleeves 34 beingintegral with the top support plate 35. Plate35 carries the hour angle gear at its periphery and they together form the hour angle gear plate 3.

As more particularly shown in FIGURES 4 and 5, the telescopes 1 and 2 are removably mounted upon the top support plate 35 by means of studs and beneath the lines of sight passing through the telescopes are mounted cuplike supports 36, within each of which is rotatably mount ed a shutter holder 41 mounting a shutter 42 and a lens system 43 in accordance with the disclosure ofthe aforesad copending application. The holder 41 is rotatably mounted through bearings 38 and 39 and the parts are maintained assembled in the cup-shaped support 36 by a cover plate 37. Beneath the shutters 32 aremounted the" phototubes 102 upon which light rays from the stars passing through the shutter 32 are focused by the lens system 43.

In FIGURES 6 and 7 is shown the drive mechanism provided for theoperation of the shutters 42. In FIG- URE 6 is shown a shutter drive gear 51 which is mounted on the end of a shaft 52 of a telescope shutter drive motor 53 mounted on the plate 35. The shutter drive gear 51 mcshes with two idlergears 54- and 55 which meshwith the shutter holders4l. The arrangement of driving and idler gears is shown in detail in FIGURE 7 whereinthe dler gears 54 and S5are"shownas rotatably mounted on the plate 35 by bearings 56 and 57 secured to the supporting plate35 by hubs 58.

In FIGURE 8is shown in. cross-section the artificial horizontal reference of"the automatic navigator. This artificial horizontal reference is mounted on frame 14 whchis carried by shaft 47 rotatably mountedin beari.ngs 45 and 46 within the hollow shaft 44atthe -left of the instrument as viewed nFIGURES 2, 4 and5. -The artificial horizontal .reference herein is similar in operation t that disclosed in applicantsPatentNo. 2,557-340- issuedJune.l9, 1951.

As shown hereinthe device includes a lamp 61 mounted wthin a lamp housing 62Which is providedwith a closing plate 63 having.a pin hole 64 therethrough. In thelight path through the pin hole is a transparent-reflecting mirror 65 from which the light rays are reflected t0the-surface of a liquid wthin a liquid pool chamber 66. The beam of 1-ight is the1i reflected fromthesurfaceof theliqudpool back through the transparent-rflecting mirror 65 to a phototube67 through a rotating shutter 68 a11d lens arrangetnent 69. The drive mechanism orthe shutten'63 of the artificial horizontal reference is similar to that which has been previoslydescribed for driving the telescopesh1tters. Itincludes a horizontal referenceshutter motor 71 having a drive gear 72 mounted on its shaft 73 with thedrive. gear 72 meshing With an idler gear74which is rotatably niounted in bearings 75 and 76 and meshes with a geredshutter holder 7'7. rotatably mounted in suitable bearingg79 and 81 and carryingthe shutter 68.

'1hehour angle plate35 is-rotated through the hour angle-gear 3 mountedthereon and meshed with a pinion driven by a motor 83 mounted on the frame 4 as shown moreparticularly in FIGURES 2 and 6. A self-synchronous motor used. as a transmtter at 84 is also mounted on the franrie4 and has its rotor driven by a'pinion meshingwith the hour angle gear 3.

In FIGURE 9 is shown the amplifier circuit and the phototube which produces the input for the amplifier circut whichenergies the restring motors;

component parts of the amplifier circuit beexplined" as associated with the Polaris telescope 1; however, itw'ill be readily undrstood that similargamplifier circuitsre assocated with both the horizontal reference lightsehsi tive circuit and the Capella telescope. In therepresnt tive system of FIGURE9 there is shown the telescope system 1, the shutter drive motor 53 driving the shiitter holder 41, the lens system43, andthe ph0totube 102..A

suitable amplifier circuit 103 containing the necessaty fil tering circuits and electronic aniplifier tubes is provided with a final amplifyng stage 111 driving a resonant cir" cut contairiing one field winding, 112 and 113, of each" of the controlled motors 12 and 24. Themotors 12 and 24 have their ether windings 114 and ll5energized from a supply voltage 116, one beingenergized directly from the supply and the other energized by the supplyvoltage shifted approxiinately electrical degrees by the effect: of a capacitor 117 connected in series therewith. The

operationof this circuit is more fully described in the a foresaid Patent No. 2,713,134." Shown in FIGURE 10 is one form of shutter usedin the present inventionwhich" consists of a dsc of treinspztrent material blacked out across one half of its surface so 'as to present a semi-circl of transparent material ai1dasemi-circle of opaque'ma-" teral to interrupt the lightbeam so as to produce a tiine phase signal fronq the phototube which is an indication of the orientation of the associatedstart More specifically, motor 53rotates by means of a gar 200 and shutterholder 41throghengagement of their teeth at 201, and a shutter 42 of the kind shown in FIG URE 10 located at the center of holder 41.

.The speed of motor 53 ismaintaintadafa desired con"- stant value. 'fhelightcoming from the light source im j pinges on a 1ens 202by which'it is focused approximately" on the plane of ;shutter 42 or shutter holder 41.1 The' light beaniemergingfron shutter42 is passed thr'ough lens system43 to befocused again on the cathodeor light sensitive electrode 204 of .photo-multipliertube 102.

This"signal is considerably amplified at the"outputjof photo-multiplier tube 102 which is operated in a well-f knovvnijconventional mariner. andis applied through bY- pss[capaitor 205 to R-.C coupled amplifier 103 consisting oftwo stages cascade, namely stage 206 and" Thecorrect filteredoutput where the filtering -occurs in ntvork 210" is applied to the power amplifier tube 111j which ha sat itsplate a circuit consisting of coils 112 and 113 in series connected between theplte 212 oftube 111 and the B+ supply shunted by capacitor 214.

Coils1l3 and 1 12 are the coilsfor restoririg motors 12a11d24 which have anotherset of coils; nainely 115 arid1l4, respectively, connected essentially in parallel to an supply 116 having a certain"preselected 'fre quency.

Actually, coil 1" 15 inseries vvith the phase changing or constant sgf1alwhich will not reach amplifier 103 be-f 202 is foc1sed away from thecenter of shutter' 42 butfl within thelirnited region covered by.shutter 42, then.the beam will becut'forevery half revolutionof shutter 4 2 and pass through shutter 42 at the other half of the r0ta- 24, mountedin quadrature. "For thesake orexample, the"- telescope with relation" to its tion of shutter 42. Thus, an A.C. signal is produced which is properly amplified by amplifier system 103 and power amplifier 111 to be finally applied to coils 112 and 113 of motors 12 and 24.

It.is necessary to point out that the function of capacitance 117 connected in series with coil 115 is to produce a phase shift between the currents flowing in windings 114 and 115 or, in other Words, capacitance 117 serves to advance the current flowing through winding 115 of restoring motor 12 by approximately 90 with respect to the current flowing through winding 114 of the other restoring motor 24.

Motors 12 and 24 will operate, therefore, on1y when the current fiowing in their field coils, namely field coils 113 and 112, respectively, has a definite phase relationship with the current flowng in coils 115 and 114 as is well-known in the art, but the phase angle of the currents flowing through coils 112 and 113 is a function of the angular position of the focusng point of the light beam comng from lens 202 with respect to the horizontal as shown, for example, in FIGURE 10 since the phase angle will depend on the particular point, angularly speaking, at which the light beam is cut o whether, for example, the light beam is cut oi as soon as the dark portion of shutter 42 starts rotating in the upper half plane or whether the beam is eut ofl during one cycle after the dark or shaded portion of shutter 42 has already rotated from the position shown in FIGURE 10 by a certain number of degrees.

Consequently, motors 12 and 24 will rotate only when the beam is not centered on shutter 42, and the amount of rotation of motors 12 and 24 will be a function of the angular position of the focus of light beam from lens 202 on shutter 42.

In FIGURE 11 is schematically shown the means by which the movements of the varous gears and transmitter may be combined in order to give an indication of longitude. The hour angle transmitter 84 is shown meshed with the hour angle gear 3 so that the hour angle selsyn transmits to the repeater 85 an indication of the position of the hour angle gear 3. A condition of unbaiance in the hour angle repeater 85 is transferred to an amplifier 86 which energizes the field windings of a balancing motor 87 which rotates in a direction to restore balance to the repeater 85 and also moves the counter mechanism of the longitude counter 88. Also incorporated into the longitude counter mechanism schematically shown in FIGURE 11 is a clock 89 which is connected to the rotor of the hour angle repeater 85 through suitable gearing mechanism so that the longitude indication will be corrected for the Greenwich hour angle of the vernal equinox thereby making the indication of the longitude counter 88 an indication of true longitude.

In FIGURE 12 is shown a latitude counter mechanism for the instrument which derives an indication from the position of the horizontal reference transmitter 80 positioned by the horizontal reference motor 13. The horizontal reference transmitter 80 transmits to the horizontal reference repeater 91 an indcation of the rotation of the horizontal reference motor 13 occasioned by movement of frame 14, by movement of sector 7, or by both. Any unbalance in the horizontal reference repeater 91 is applied to the amplifier 92 which energizes the motor 93 to rotate the rotor of the repeater in a direction to restore electrical balance to the repeater. Motor 93 also positions latitude counter mechanism 94.

The nterconnecting electrica=l wiring which would be obviously necessary in the operation of the device of the present invention has not been shown, but it is believed to be readily apparent that such wiring could be connected through terminal boards as are shown in FIG- URE 3 at 95, 96 and 97. It is further understood that interconnection between the moving parts of this present device and any remotely associated parts may be made through suitable slip ring connections, not shown.

The axis of the Polaris telescope is made perpendcular to the plate 35 for uniformity and ease of manufac- In this description of the operation of the present invention, the two stars upon which continuous tracking will be maintah1ed are selected as Polaris and Capella. With the telescope. 1 directed at Polaris, the rays of light therefrom are deviated through the prism 101, and directed onto the cathode of the phototube 102 so that a timephase signal will be produced in accordance with the alignment of the resultant optcal axis of the telescope and Polaris. The signal produced by the phototube 102 is applied to the amplifier circuit 103 to energize the motors 12 and 24. The operationof the shutter motor, the shutter, the phototube, the amplifier stages, and two phase energizaton of the field windings of the two restoring motors in accordance with the position and time phase interruption of the light beam by the shutter is fully described in the aforesaid Patent No. 2,713,134. The two motors which are energized by the alignment of telescope 1 on the star Polaris are the azmuth motor 24 which rotates the entire device about an axis normal to the mounting plate 29 until the telescope is ponting north and the elevation motor 12 which rotates the frame 4 about the axis through shafts 44 to align telescope 1 for the proper elevation of Polaris. With telescope 1 aligned on Polaris, the device has now been adjusted so that an indication is provided of true north and so that the plane of the hour angle gear 3 has been aligned in parallel with the equinoctial. The teleseope 2 is now directed toward the star Capella and the light rays from the star Capella are passed through the lens of the telescope, reflected from the reflectng mirror 104 and directed through the associated shutter 32 and lens system 43 onto the oathode of the associated phototube 102 which energizes -an associated motor actuating amplifier 103 as has been previously described in connection with the Polaris telescope. The output of this amplfier is used to actuate the north-south axis motor 23 to rotate the cradle 11 by moving the race 15 relative to the race 16 about an axis normal to the axis through the shaft 44 and correspondng to the axis of development of the races, untl the device is adjusted to the proper elevation of Capella to ndrectly cause the alignment of the telescopes for the proper hour angle.

The artificial horizontal reference produces its own beam of light from source 61 through aperture 64 and has this reflected from the surface of the liquid pool in the chamber 66 through 2. lens, shutter and phototube arrangement similar to that previously described in connection with the two telescope circuits. A third amplifier circuit 103 is assooiated with the horizontal reference phototube to produce two motor actuating voltages which actuate the horizontai reference motor 13 and the hour angle motor 83 to return the artificial horizontal reference into coincidence with the local vertical, the action of motor 13 about the axis of shaft 47 being direct, whle the action of motor 83 operates directly to rotate the hour angle gear 3 and only ndrectly upon the horizontal reference through the resultng response of motor 23 caused by the deviation of Capella from its correct alignment caused by the rotation of the hour angle gear 3 and the plate '35.

As an example of the operation of the device here shown, assuming a change in latitude by travel along any of the meridians a.fter the two telescopes have been will be accompanied by energizatin of the motor 1210 eect rot-aton of the frame 4 about the axis of the shafts 44 to. change the elevation angle of telescope-1 to maintion of the sector 7 is therefore accompanied by rotation of the frame 14 and. the horzontal reference mounted thereon so that the surface of the liquid in chamber 66 is tilted with respect to the path of the light beam directed:tzhereon. This tilting and resultant deviation of the light beam from the center of the associated-shutter 68 -affects energization of the motor 13 only to rotate the frame 14 about shafts 47 untiithe surf-ace of the liquid is again normal to the light=path directed to and reflected therefrom. Since the tilt of the liquid surfaee is about an axis parallel to the shaft 47,ohly the motor 13is energized for resto ration Motor 13v also rotates the transmtt er 80 to, eiect an unbalance in the repeater 91 which is connected by motor 93 with consequent change in the latitudewounter 94.

.A ohange in longitude only of the instrument after ori entationcauses a deviation in azimuth between the axes of the telescopes and the stars which they seek. This will efec t energization of the motor 24 to rotate the;device b odily about an aijris nonnal to the mount ing plate 29 to align thetelescope 1 with Polaris. 'Ihis rotation causes telescope 2 to deviate from the alignment with Capella so that motor 23 is energized to rotatethe. cragile 11 about thenorth-south axis at ;right angl es to theaxis through shaft144. This rota tion of cradle 11 also rotates the frame 14 and the horizontal reference mounted thereon about the north-south axis so that the surface of the lquid in chamber 66 is tilted with respect to the light beam directed thereon. 'Ihis deviation of the horizontal reference aiects energization of the motor 83 to rotate the hour angle gear 3 and the plate 35 on which it is mounted. Rotation of the cradle 11 about the north-south axs also tends to cause telescope 1 to deviate from alignment with Polaris which afiects energization of its motors to restore it to align ment. The restoring act-ion of the motors 12, 23, 24 and 83 continue in this inter-related manner to maintain the telescopes 1 and 2 in alignment with Polaris and Capella and the surface of the liquid in chamber 66 normal to the light beam directed to and reflected therefrom. The rotation of the hom angle gear 3 resulting from the above movements causes rotation of the transmitter 84 to eiect -an electrical unbalance in the 'repeater 85 so that the motor 87 is energized to restore the electrical balance to the repeaters. The sidereal clock 89 is also changing the electrical balance of the repeater 85 and the resultant is reflected in truc longitude at the counter 88.

It will be understood that the movements and corrections described in the above explanation of the eflect of movement in either longitude or latitude or both are not individual in nature and that the motors of the device are in continuous operation while the device is being moved to maintain the telescopes in alignrnent with ther pre selected points of reference and the liquid surface in the horizontal reference in alignment with the local hori zontal.

The operation of the Capella telescope When the air or sea craft upon which it is mounted is not moving is to follow the star Capella around its diurnal path and to introduce a correction for the Greenwich hour angle of the vernal equinox so as to retain a constant indication of longitude. This is accomplished through the use of the difierential repeater selsyn shown at 85 in FIGURE 11, the stator of which is energized by the hour angle selsyn 84 and the rotor of which is rotated by the clock mechanism 89. When the craft on which the instrument is mounted is moving in the same direction as the sun,

the stator of the diierential hour angle repeater is? energizedtoindicate the propr-movement of the Capella telescope 2.= The rotor of the difierental repeater 85 is physically moveds-by clock mechanism 89 to ;develop an effectivemotion between thestator and rotor which prodces.an unbalance in the repeater. Thisunbala1ice- When applied to the .amplifier86 energizes theniotor 87 to rotatethe housing. of the repeater 85 to bring the repeater 85 to an electrcal balance and to move the longitude counter mechanism toindicate the change in longitude. When the.zcraft is movingin an easterlydirection, the movement ofthe Cpella telescope 2 causedbythemovement of the craft isadded"tothe movement caused by the travel of the star in its diurnal path so as toelectrically move the energizatiori of the stator of the repeater85 a greater distance than the mechanical move ment ofthe rotor; causediby the clock 89. Again the unbalance is applied totheamplfier 86 and the motor 87 is1thereby energized to rotate thehousing of thempeater 85 to.returnthe repeater 85 to balance and to move the longitudefcounter mechanism 88-to-indicate thedecreaseinlongitude. ;j

It will thl s jbe:.seen thatthe Polaris telescope in 60- operationwith; the:means levelingtheaxis of shafts 44 causestrue alignmentof the automatic navigator; that the Capella telescope brings in compensations for rota don of the:earth withinthecelestial sphere; and;thatthe artificial horizontal reference=section correctsfor move-- ment ofthecraftupon-the surface of the earth, the resulting indications and responses reflecting the, true. latitude and: longitud e of theinstrument While certainpreferred embodiments of tiieinvention have been specifically disclosed, t is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the i11- vention is to be given its broadest possible interpretation within the terms of the following claims:

What is claimed is:

1. In an automatic navigator, a support havng three mutuallyperpendicular axes of rotaton, means m0unt ing said support for rotation about a fourth axis, a plurality of telescopes mounted on said support in fixed angular relationship, said angular relationship being predetermined so that said telescopes are directable toward preselected celestial points of reference, radiant energy responsive means associated with said telescopw means energized by said madiant energy responsive means for positioning said support about said mutually perpendicular axes, means providing a horzontal reference, means for positioning said horizontal reference into eoincidence with the local horizontal, means responsiVe to deviation of said reference from the horizontal for energizing said reference positioning means, means for rotatng said sup+ port about said founth axis, and means for energizing said last men-tioned means from said deviation respons1ve means.

2. In an automatic navigator, a support having three utually perpendicular axes of rotation, means mount ng said SHPPOI for rotation about a fourth axis, a plurality of telescopes mounted on said support in fixed angular relationship, said angular relationship beng predetermined so that said telescopes are directable toward preselected celestial points of reference, radiant energy responsive means associated with said telescopes, means energized by said radiant energy responsive means for post-ioning said support about said mutually perpendicular axes with said fourth -axis at right angles to theplane of the celestial equator, means providing a hori- 11 and sad fourth axis to derive the latitude of the navigator.

3. In an automatic navigator, a support having three mutually perpendicular axes of rotatou, means mounting sad support for rotation about a fourth axis, a plurality of telescopes mou.uted on sad support in fixed angular relationship, sad angular relationship being predetermined so that sad telescopes are directable toward preselected celestial ponts of reference, radiant energy responsive means associated With sad telescopes, means energized by sad radiant energy responsive means for postioning sad support about sad mutually perpendicular axes With sad fourth axis at right angles to the plane of the celestial equator, means providing a horizontal reference, means for postioning sad horizontal reference nto coincdence with the local horizontal, means responsive to deviation of sad reference from the horizontal for energizing sad reference positiom'ng means and for rotating sad support about sad fourth axis, means providing Greenwch sidereal time, and means for continuously and automatically ndcating the comparson of the angular rotation of sad support about sad fourth axs with Greenwch sidereal time to derive the longitude of the navigator.

4. In an automatc navigator, a support having three mutually perpendicular axes of rotation, means mounting sad support for rotation about a fourth axis, a plurality of telescopes mounted on sad support in fixed angular relationship, sad angular relationship being predetermined so that sad telescopes are directable toward preselected celestial points of refereuce, radiant energy responsive meaus assocated with sad telescopes, means energized by sad radant energy responsive means fox positioning sad angular rotation of sad support about sad fourth axs' with Greenwich sidereal time to provide an indication of the longtude of the navigator, and means for continuously and automatically indicating the relationshp be-.

tween the local horizontal and sad fourth axs to indicate the latitude of the navigator.

References Cited in the fi1e of this patent UNITED STATES PATENTS 2,007398 Clark Apr. 20, 1937 2,102587 Elie1 Dec. 21, 1937 2,155,402 Clark Apr. 25, 1939 2444933 Hasperson July 13, 1948 2462,925 Varian Mar. 1, 1949 2,471,686 Hiltner May 31, 1949 2492,148 Herbold Dec. 27, 1949 2,513,367 Scott Ju1y 4, 1950 2,532,402 Herbold Dec. 5, 1950 FOREIGN PATENTS 105,371 Great Britan Apr. 5, 1917 33,746 Netherlands Oct. 15, 1934 

